Fixing argparse and JSON / PDF verification tasks

[deadbits]

This was branched from your Revert "Revert "converted to argparse library"" branch so this PR should fix both the argparse revert problem and adds the following from the branch pdf_cleanup:

• check if output filename exists
  • create new output file based on timestamp if so
• check if PDF exists
  • delete opened output file if PDF does not exist
  • stop execution
• adds function to generate string friendly timestamp for filename creation

[sroberts]

So if i give a -o foo.json for output and foo.json doesn't exist it will hard stop? That wasn't what I had in mind, and certainly not how I use it.

[krmaxwell]

Looking at it, it stops if the input PDF doesn't exist (not the output JSON, which we don't care if it exists previously because we're going to blow it away anyway)

[deadbits]

yeah @krmaxwell has it right. if the input PDF doesn't exist the app will rm the output file and then exit

[sroberts]

Ahhh ok. In that case good by me, anyone else before I merge? :shipit: